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package fish.payara.microprofile.telemetry.tracing.jaxrs;

import jakarta.ws.rs.container.ResourceInfo;
import java.lang.reflect.Method;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Supplier;

class ResourceCache<T> {

    private static class ResourceKey {
        Class<?> resourceClass;
        Method resourceMethod;

        @Override
        public boolean equals(Object o) {
            if (this == o) {
                return true;
            }
            if (o == null || getClass() != o.getClass()) {
                return false;
            }
            ResourceKey that = (ResourceKey) o;
            return resourceClass.equals(that.resourceClass) && resourceMethod.equals(that.resourceMethod);
        }

        @Override
        public int hashCode() {
            return Objects.hash(resourceClass, resourceMethod);
        }

        ResourceKey(ResourceInfo info) {
            this.resourceClass = info.getResourceClass();
            this.resourceMethod = info.getResourceMethod();
        }
    }

    private final ConcurrentHashMap<ResourceKey, T> tracedCache = new ConcurrentHashMap<>();

    T get(ResourceInfo info, Supplier<T> supplier) {
        return tracedCache.computeIfAbsent(new ResourceKey(info), k -> supplier.get());
    }

    /**
     * clear all classes belonging to this class loader
     * @param classLoader
     */
    void clear(ClassLoader classLoader) {
        tracedCache.entrySet().removeIf(entry -> entry.getKey().resourceClass.getClassLoader() == classLoader);
    }
}
